The search for better fuel economy takes engineers down weird paths, and the latest plan to wring out extra mileage is no different. It involves an unlikely part of the vehicle — the suspension.
Audi just announced a new suspension system that harvests wasted energy and turns it into electricity, capable of adding juice to a vehicle’s 48-volt electrical subsystem.
The automaker calls the system “eROT” after the electromechanical rotary dampers that capture kinetic energy and store it in a battery. Currently in the prototype phase, the system does away with conventional shock absorbers, replacing them with lever arms connected to a small gearbox and alternator.
“Every pothole, every bump, every curve induces kinetic energy in the car,” said Stefan Knirsch, Audi’s technical development boss, in a release. “Today’s dampers absorb this energy, which is lost in the form of heat. With the new electromechanical damper system in the 48-volt electrical system, we put this energy to use. It also presents us and our customers with entirely new possibilities for adjusting the suspension.”
The lever arm absorbs the motion of the wheel carrier, transferring the power to an electric motor through a set of gears. The motor converts that force into electricity, which is stored in the system’s 0.5 kilowatt-hour battery. That battery has an output of 13 kW, and can feed the vehicle’s generator, leading to a slight improvement in fuel economy.
During an average drive, the system is able to capture between 100 and 150 watts of energy, Audi claims. Rough roads mean greater energy capture, while smooth-as-glass highway jaunts might harness just a few watts.
The system’s benefits are many. Not only does it boost mileage, it would it allow drivers to adjust their ride comfort via the freely programmable dampers. Also, the lack of upright shock absorbers means more trunk space. Audi says the system’s appearance on future vehicles is “certainly plausible.”
The automaker plans to test a beefed-up version of the system in a mild hybrid vehicle next year, with the upgraded eROT expected to boost mileage by 0.7 l/100 km.